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I'm going to buy a PoE injector kit, and I will supply it with an AC voltage, and with ethernet cable, and at the other end I will design a seperator circuit, but however most PoE injectors just give 40DC, with at most 400mA. I would like to get more amperage at the backend, is it a must to have a battery or any other supplier and put some transistors to get more current ?

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Do you need to be PoE compatible? Just a quick read on existing PoE and it seems you can negotiate for slightly more power than that. Finally, if the power is bursty, then you can store charge locally on the device in a battery/capacitor/... – kenny Jan 17 '13 at 11:39
Yea, because I also need the data lines – Mahmoud Jan 17 '13 at 12:03
With a 8 conductor RJ45 there is plenty of wire to run any data protocol you want including Ethernet and have power supplied in a way that isn't compatible with PoE. – kenny Jan 17 '13 at 12:09
@kenny Not true of gigabit ethernet, which uses all four pairs. – Phil Frost Jan 17 '13 at 15:39
I am also interested in injecting more power than standard PoE can provide. I'd be surprised if this is possible without going non-standard on both ends. – Andrew Wagner Mar 4 '14 at 17:48
up vote 0 down vote accepted

IEEE 802.11at (PoE+, PoE plus) can provide 25.5 W, about twice that of the previous 802.11af standard. It's common for recent wireless access points to require this higher-power implementation.

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There are new standards coming out soon for UPOE for 60W and many non standard devices on the market that will deliver up to 51W. There are also non standard devices that go up to 96W. This is the theoretical limit for keeping the devices at safe voltage and current levels due to ITE standards.

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